scsi_alloc_consistent_buf(9F)

NAME

scsi_alloc_consistent_buf − allocate an I/O buffer for SCSI DMA

SYNOPSIS

#include <sys/scsi/scsi.h>

struct buf ∗scsi_alloc_consistent_buf(struct scsi_address ∗ap, struct buf ∗bp,

int datalen, ulong bflags, int (∗waitfunc )(caddr_t), caddr_t arg);

INTERFACE LEVEL

Solaris DDI specific (Solaris DDI).

ARGUMENTS

ap Pointer to the scsi_address(9S) structure.

bp Pointer to the buf(9S) structure.

datalen Number of bytes for the data buffer.

bflags Flags setting for the allocated buffer header.

waitfunc Pointer to either NULL_FUNC or SLEEP_FUNC.

arg waitfunc function argument, must be NULL.

DESCRIPTION

scsi_alloc_consistent_buf() allocates a buffer header and the associated data buffer for direct memory access (DMA) transfer. This buffer is allocated from the iobp space, which is considered consistent memory. For more details, see ddi_iopb_alloc(9F) and ddi_dma_sync(9F).

For buffers allocated via scsi_alloc_consistent_buf(), and marked with the PKT_CONSISTENT flag via scsi_init_pkt(9F), the HBA driver must ensure that the data transfer for the command is correctly synchronized before the target driver’s command completion callback is performed.

If bp is NULL, a new buffer header will be allocated using getrbuf(9F). In addition, if datalen is non-zero, a new buffer will be allocated using ddi_iopb_alloc(9F).

waitfunc indicates what the allocator routines should do when direct memory access (DMA) resources are not available; the valid values are:

NULL_FUNC Do not wait for resources. Return a NULL pointer.

SLEEP_FUNC
Wait indefinitely for resources.

RETURN VALUES

scsi_alloc_consistent_buf() returns a pointer to a buf(9S) structure on success. It returns NULL if resources are not available and waitfunc was not SLEEP_FUNC.

CONTEXT

If waitfunc is SLEEP_FUNC, then this routine may be called only from user-level code. Otherwise, it may be called from either user or interrupt level. The waitfunc function may not block or call routines that block.

EXAMPLE

    bp = scsi_alloc_consistent_buf(&devp->sd_address, NULL,
         SENSE_LENGTH, B_READ, SLEEP_FUNC, NULL);
    rqpkt = scsi_init_pkt(&devp->sd_address,
         NULL, bp, CDB_GROUP0, 1, 0,
         PKT_CONSISTENT, SLEEP_FUNC, NULL);

Museum

Related Articles